A method of making a three-dimensional object by laminating sintered layers is known in, for example, Japanese Laid-Open Patent Publication No. 1-502890, wherein an optical beam (directional energy beam, for example, a laser) is first irradiated on a powdery layer formed on a support base to form a sintered layer. The sintered layer thus obtained is then covered with a new powdery layer, on which the optical beam is irradiated to form a new sintered layer. These processes are repeatedly carried out to form a three-dimensional object in which a plurality of sintered layers are laminated one above another.
A method of finishing a surface of a shaped object, i.e., a laminated body made up of the sintered layers in the middle of the manufacture of the three-dimensional object is disclosed in, for example, Japanese Laid-Open Patent Publication No. 2002-115004.
As shown in FIG. 19A, when an optical beam is irradiated on a predetermined portion of a powdery layer 10 for selective sintering, sparks scatter and a residue of molten powder contained in the sparks sometimes adheres to a surface of a sintered layer 11, as shown in FIG. 19B, resulting in abnormal sintering 19 in the form of protrusions.
In applications where finish machining is conducted during the laminating process of the sintered layers 11, working scraps (cutting scraps) scatter, and if such working scraps give rise to protrusions on a surface of the next powdery layer 10, there is a good chance that abnormally sintered portions 19 in the form of protrusions may be produced during subsequent sintering.
In applications where each powdery layer 10 is set to have a thickness of 50 μm in order to obtain a three-dimensional object having a high density and a high geometry, powder particles have a diameter of about 10-50 μm. In this case, if the abnormally sintered portions 19 are produced, there is a fairly good chance that they may protrude upwardly from a surface of the subsequent layer 10, and a leveling blade for leveling the surface of the powdery layer 10 may be brought into contact with the abnormally sintered portions 19, thereby stopping the shaping process.
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly an objective of the present invention to provide a method of and apparatus for making a three-dimensional object that is free from a stop of the shaping process, which has been hitherto caused by the abnormally sintered portions.